Biosignals are mostly used for registering image datasets of moving objects. A known instance thereof in the case of a living thing is the ECG signal. The image series datasets can therein derive from an imaging modality at different instants, they can have been recorded based on a plurality of imaging modalities at the same instant, or they can derive from different modalities at different instants. Image datasets containing a plurality of single images recorded at different instants within the periodic motion will be referred to below as image series datasets. However, a prerequisite for the use of biosignals for temporal registration is that the frequency of the biosignal does not change between measuring instants. If it does, as in the case of, for instance, cardiac arrhythmia, the result will be a misregistration of the image series datasets. It will hence not be possible to assign instants of the biosignal at a first examination instant one-to-one to the instants of the biosignal at a second examination instant.